1. Field
The present disclosure relates to a fuel cell stack.
2. Description of the Related Art
For example, a solid polymer electrolyte fuel cell includes a solid polymer electrolyte membrane, which is a polymer ion-exchange membrane. The fuel cell includes a membrane electrode assembly (MEA), in which the solid polymer electrolyte membrane is disposed between an anode electrode and a cathode electrode. The anode electrode and the cathode electrode each include an electrode catalyst (electrode catalyst layer) and porous carbon (gas diffusion layer). The MEA and separators (bipolar plates), sandwiching the MEA therebetween, constitute a power generation cell. A fuel cell stack is formed by stacking a predetermined number of such power generation cells and is used, for example, as an automobile fuel cell stack.
In a fuel cell stack, there are some power generation cells whose temperatures tend to become lower than those of others due to dissipation of heat to the outside. For example, heat of a power generation cell that is disposed at an end of the fuel cell stack in the stacking direction (hereinafter, referred to as an “end power generation cell”) is dissipated by a large amount from, for example, a power output terminal plate (current collector plate), an end plate, and the like. As a result, the temperature of the end power generation decreases considerably.
As the temperature of the end power generation cell decreases, condensation more likely occurs on the end power generation cell than on power generation cells disposed at a central part of the fuel cell stack. Therefore, a problem arises in that generated water is not smoothly discharged and the power generation performance is reduced.
For example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-526366 discloses a fuel cell that addresses this problem. As illustrated in FIG. 11, the fuel cell includes a stacked body, in which cells 1 are stacked, and end plates 2a and 2b disposed at respective ends of the stacked body. A cooling system 3 is disposed in the fuel cell. The cooling system 3 includes a circulation duct 4 extending through the cells 1 in the stacking direction. A fluid pump 5 circulates a coolant through the circulation duct 4.
Heat extraction units 6 are disposed outside of the end plates 2a and 2b. Each of the heat extraction units 6 includes a plurality of heat pipes 7, and the heat pipes 7 are inserted into the end plates 2a and 2b. The heat pipes 7 receive heat from the coolant flowing through the end plates 2a and 2b along the circulation duct 4, and therefore the cells 1 can be cooled rapidly.